Reports of discovery of a database, accessible on the internet, containing voter records of 191 million Americans, has alarmed many privacy advocates and concerned citizens. Yet the most remarkable thing about this database is simply that it’s in a convenient form, or at least convenient for those with just the right technical skills to find and use it.

One thing that is private everywhere: how you voted. The contents of ballots are always secret.

Other voter data is largely a matter of public record. It’s collected for public purposes, not private ones, and there’s no opt-out on sharing this information. Voter records may contain facts about individuals, including…

Name

Street address

Party affiliation

Elections in which you did (or did not) vote

Phone number

Email address

And how can the data be used? While each state sets its own rules, voter data from every state is available for some uses. If you’ve noticed poll watchers at your polling place, you were seeing voter data in action, used by a campaign to keep track of who has and has not voted, to guide phone banks and other efforts to bring out the vote. Many states put no restrictions on use, so voter data may also be used for issue politics, charitable solicitation and commercial marketing.

But voter data records are not necessarily easy for most people to obtain or use. Reaching out to governments for data requires a certain level of know-how just to make the request, let alone to work with large and often complex data files. That’s why specialists, such as GOP Data Center (for Republicans) and NGP VAN (for Democrats) supply data in accessible forms for election campaigns. Political software firm NationBuilder has released a statement acknowledging that some of the data may have come from “data [NationBuilder makes] available for free to campaigns.”

These specialists make it easier for political campaigns to do their work. Effective use of the voter database was a major factor in the 2008 and 2012 Obama for America campaigns. (I wrote more about use of this data by the Obama for America campaign in the book, Data Mining for Dummies. You can find it in many public libraries.)

Voter data vendors don’t want public releases of their databases. They invest in getting the data well-organized to make it available to their clients, not hackers. But movement of data can be hard to control, as this incident, and the recent breach of a Democratic voter database make clear.

Meta S. Brown is author of Data Mining for Dummies and creator of the Storytelling for Data Analysts and Storytelling for Tech workshops. http://www.metabrown.com.

I’m author of Data Mining for Dummies, and creator of the Storytelling for Data Analysts and Storytelling for Tech workshops. My work focuses on two challenges: 1) helping technical experts communicate effectively with everyone else, and 2) providing guidance for organizatio...